A method for producing three-dimensional models from computer data is described in the European patent specification EP 0 431 924 B1. A first material, a particulate material in this case, is applied in a thin layer onto a building platform, which, if necessary, is surrounded by a container, and a second material, which may form a solid with the first material, is subsequently applied thereupon. According to EP 0 431 924 B1, a particulate material is provided, for example, as the first material, and a binder material is then selectively printed onto the particulate material using a print head. The particle area onto which the binder is printed sticks together and solidifies under the influence of the binder and, if necessary, an additional hardener. The platform is then lowered by a distance of one layer thickness into a build cylinder and provided with a new layer of particulate material, which is also printed as described above. These steps are repeated until a desired height of the model is achieved. A three-dimensional model is thereby produced from the printed and solidified areas.
After it is completed, the model produced from solidified particulate material is embedded in loose particulate material and is subsequently removed therefrom.
Other powder-supported rapid prototyping processes work in a similar manner, for example selective laser sintering or electron beam sintering, in which a loose particulate material is also deposited in layers and selectively solidified with the aid of a controlled physical radiation source.
All these methods are referred to collectively below as “three-dimensional printing methods” or 3D printing methods.
Another method for constructing a layered body from loose particulate material is known from WO2011/127897A2. The build process takes place according to the “continuous 3D printing” principle and is another variant of the powder-processing 3D printing method.